Field of the Invention
The present disclosure relates to devices and methods for extending the shelf life of rechargeable batteries.
Description of the Related Art
Modern battery technology is primarily focused on the use of primary cells or secondary cells, such as typical rechargeable cells, to comprise a primary or secondary battery.
Primary batteries may be useful in situations where a long shelf life is desirable. For example, many primary batteries may be able to remain unused for over ten years without losing significant capacity. However, since primary batteries typically cannot sustain high discharge rates, their use is generally limited to low discharge applications.
Secondary batteries, such as typical rechargeable batteries, may offer the ability to discharge much more rapidly than primary batteries. In addition, unlike primary batteries, rechargeable batteries may be recharged after discharge. However, secondary batteries typically have a much more limited shelf life than primary batteries. For example, a rechargeable battery may lose approximately 1-5% of battery capacity per month of storage. This loss of battery capacity may limit the shelf life of a secondary battery such as a typical rechargeable battery for various applications. After a sufficient period of time, the aggregate loss of battery capacity from secondary batteries in storage may lead to the secondary batteries having insufficient battery capacity to adequately support certain applications. For example, a fully-charged secondary battery may lose approximately 5% of its battery capacity in the first month of storage and then around 2% thereafter. In such a situation, the secondary battery may lose approximately 27% of its initial battery capacity in the first year. After 1.5 years, the secondary battery may be considered dead (e.g., having 70˜80% of the original battery capacity).
Various applications may require the use of batteries that may be stored for years prior to use and yet still be able to discharge at a rapid rate. Thus there remains a significant need for a battery that both has a long shelf life and is capable of discharging at a rapid rate.